MXPA99007132A - Sell metal container - Google Patents

Abstract

The present invention relates to a sealed metal container for holding a material of relatively low viscosity, the container comprising: a base having sides, upper and lower, a formed side wall member that engages the upper side of the base to form a bottom seam, the opposite ends of the side wall member being engaged with one another to form a side seam, the side wall member defining the top side and an inner surface of the container, and a sealing compound including a mixture of synthetic wax and adhesive, the compound having a sufficient fraction of adhesive to allow binding of the compound to the inner surface of the container, the sealing compound having when bonded, a flexibility of about 10 to 20 pounds per inch, a hardness of about 0.01 to 0.3 mm for 100g / 5 seconds / 25ºC and a melting point of at least 80

Description

SEALED METAL CONTAINER FIELD OF THE INVENTION The present invention relates generally to containers and, more particularly refers to sealed metal containers and methods for making them. BACKGROUND OF THE INVENTION A wide variety of products are packaged in metal containers. Metal containers are desirable because they are durable and provide a distinctive appearance. The metal containers can additionally be formed in various configurations and sizes and decorated with illustrations. As a result, metal containers are often used to hold consumer products. It is important that the metal container adequately conserve the contained product. Many products have a low viscosity and therefore flow easily through cracks or seams in the packaging. For example, products such as lotions, creams and candles are heated during processing to obtain a flowable material that is processed and packaged more easily. In addition, products such as candles experience elevated temperatures when the consumer uses them for the proposed purposes, and consequently creates a flowable material again. The metal containers used to hold these products must therefore be able to retain material that has low viscosity. Previously, glass jars and stretched metal containers have been used to easily maintain flowable materials. These conventional containers are typically formed as a single unitary piece, so that they are formed seamlessly through which the material can be spilled. The production of these previous containers in various shapes and sizes requires a large re-equipment of machines, and therefore is excessively expensive and time-consuming. In addition, it is difficult to improve the appearance of those containers with illustrations. Relatively deep stretched metal containers, for example, require to apply illustrations to a flat blank in distorted form so that, after the container is tied in the shape, the illustration is bent into the proper visual appearance. However, the design and application of distorted illustrations is excessively difficult and expensive. It is known that containers formed of multiple pieces are less expensive to be made in different shapes and sizes, and easier to decorate. For example, a standard three-piece metal container has a base and side wall attached to form the container and a removable cover. The side wall is formed of a flat metal strip which is then folded or rolled into a cylinder, square or other shape, either regular or irregular. The ends of the side wall join to complete the shape. The base is generally flat and is formed to be fixed to a lower edge of the side wall. Finally, the cover is a separate piece that is dimensioned to be removably fixed to the upper edge of the side wall. Unfortunately, multi-piece metal containers create an increasing risk of product leakage. From the above, it is evident that a number of seams are formed between the different components of the three-piece metal container. A seam is formed along the height of the side wall of the container where the opposite ends of the metal strip meet. In addition, a seam forms around the entire periphery of the side wall where it joins the base. As a result, materials that have low viscosity can spill through the seams of the container. The containers of previous candles have used several proposals to avoid spills through the seams of the container. Some containers, for example, have carefully formed seams that fold tightly. However, these tight seams are difficult to form and do not reliably avoid spills. Other containers have used volatile or hazardous materials (such as materials based on methylethyl ketone (MEK)) to seal the seams of the container and therefore present a threat to the environment. further, these materials are typically applied by hand to the container (or "are varnished by hand") and therefore require expensive manual labor. SUMMARY OF THE INVENTION In view of the above, a general object of the present invention is to provide a stitched metal container that is reliably sealed with a non-hazardous sealing compound to thereby adapt the container for use with materials of relatively low viscosity. In this regard, it is an object of the present invention to provide a stitched metal container that is reliably sealed for use in applications that include elevated temperatures. A related object of the present invention is to provide a sealed metal container adapted for use with candles, which minimizes the burn of the surface on which the container is placed.

It is also an object of the present invention to provide an automatic method for sealing a stitched metal container so as to retain flowable materials. In this regard, it is an object of the present invention to provide an automatic method for sealing a stitched metal container, which reliably covers the seams of the container. In view of the foregoing, the present invention provides a stitched metal container having an interior surface coated with a non-hazardous sealing compound. The sealing compound forms a barrier that prevents the spillage of the low viscosity material, flowable through the seams. More particularly, the sealing compound comprises a mixture of synthetic wax with a sufficient amount of adhesive, so that the mixture sticks to the inner surface of the container and seals the seams. It is also a feature of the present invention to provide a support flange around the base of the metal container that separates the base from the surface on which the container is placed. The support flange is formed around the periphery of the base so that, when the container is placed on a surface, only the flange is in contact with that surface. As a result, when the container holds a material at an elevated temperature, such as a burning candle, a greater part of the base is separated from the surface to create an air-insulating bag that reduces the burn of the surface by the base. The present invention further provides a method for reliably sealing a stitched metal container that is automatic and therefore reduces labor costs. The method requires that the sealing compound be heated, pressurized and sprayed through a nozzle. The nozzle is inserted into an uncoated container and moves along the. length of the container as it sprays to coat an interior surface. These and other objects, advantages and features of the invention will be more apparent from the following detailed description when taken in relation to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a stitched metal container, constructed in accordance with the present invention. Figure 2 is a side, cross-sectional view of the metal container taken along line 2-2 of Figure 1. Figure 3 is a side, cross-sectional view of the metal container taken along line 3-3 of Figure 1. Figure 4 is a partial schematic representation of the equipment used to spray a sealing compound over the interior of the container, showing a nozzle positioned near the base of the container. Figure 5 is a partially schematic representation similar to Figure 4 showing a nozzle positioned near the top of the container. Although the invention is susceptible to various modifications and alternative constructions, certain embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood that, however, there is no intent to limit the invention to specific forms described, but rather, the intention is to cover all modifications, alternative constructions and equivalents that fall within the spirit and scope of the invention as defined by the appended claims. DETAILED DESCRIPTION OF THE PREFERRED MODALITY For purposes of illustration, the invention is shown in Figure 1 as embodied in a sealed metal container 10 adapted to hold a product such as a candle 12. The interior of the container 10 is coated with a sealing compound 14 that prevents the material - flowable, such as melted candle wax, spills from the container. Although the present invention has been illustrated as holding a candle, it will be appreciated that the sealed metal container 12 is capable of maintaining a wide variety of products., including liquids that have a relatively low viscosity. The sealing compound 14 comprises a synthetic wax and an adhesive, as will be described below. Referring to the container 10 in greater detail, it will be noted that the container generally comprises a base 16, a side wall 18 and a cover 20. As best shown in Figure 2, the base 16 is formed with a dependent flange 22, which is extends around a periphery of the base 16. The rim 22 separates the bottom side 26 of the base 16 from a support surface 24, on which the container is placed, such as a board. Therefore, the flange 22 creates an insulating space 28 between the lower side 26 of the container and the supporting surface 24. As a result, only the flange is in contact with the supporting surface 24, thus reducing the surface area of the substrate. support that can be burned when the container 10 is at an elevated temperature. The side wall 18 comprises a single strip of relatively thin sheet metal that is formed in a shape corresponding to that of the base 16. As best shown in Figure 3, the side edges 31, 32 of the side wall 18 are they engage with one another to complete the shape of the container 10. The side wall 18 has an inner side 33 which meets the upper side 35 of the base to define an inner surface of the container. The side edges 31, 32 of the side wall 18 are folded over one another to form a side seam 34. A bottom edge 36 of the side wall 18 is bent with an outer edge 27 of the base 16 to form a lower seam 38 around the entire perimeter of the container 10. In the illustrated embodiment, the side wall 18 is formed to have a generally square shape, however circular, rectangular or other shapes (both regular and irregular) may also be formed. The cover 20 is provided to close the upper part of the container 10. As shown in Figure 1, the cover 20 has a flat portion 40 with a dependent wall 42. The shape of the wall 42 corresponds to that of the side wall 18. The wall 42 is dimensioned so that it can be installed on an upper portion of the side wall 18 and held in place in a press fit manner. The cover 20 can be removed by pulling up the cover until the wall 42 disengages the side wall 18.

In accordance with certain aspects of the present invention, the inner surface of the container 10 is coated with the sealing compound 14 to prevent the flowable material from spilling through the seams, lateral and bottom, 34, 38. As best shown in Figures 2 and 3, a layer of sealing compound 14 is bonded to the inner surface of the container 10, which includes the inner side 33 of the side wall 18 and the upper side 35 of the base 16. The sealing compound 14 prevents flow of the flowable material through the seams 34, 38. In accordance with the present invention, the sealing compound 14 must be sufficiently hard to form a substantially impermeable but sufficiently flexible layer to minimize cracking.

As noted above, container 11. is preferably made of relatively thin sheet metal and is therefore somewhat flexible. The sealing compound 14 must therefore be bonded to the inner surface and resist bends without cracking. A test procedure for measuring flexibility is provided under ASTM D 2794, incorporated herein by reference. ASTM D 2794 provides a standard test method for the strength of organic coatings for the effects of rapid deformation. Under the method, the organic coatings are applied to a thin metal panel. Then, a weight is dropped at a known distance to hit the metal panel, thereby deforming the coating. The distance at which the weight falls increases until the failure, which takes the form of a crack. According to this method, it has been found that a preferable range of flexibility for the sealing compound 14 is about 10 and 20 pounds per inch, and more preferably about 12 pounds per inch. A method for testing hardness is provided under ASTM D 1321-95, incorporated herein by reference. ASTM D 1321-95 provides a standard test method for the penetration of ag ja from petroleum waxes. A test sample is heated to a test temperature and a needle is inserted into the sample at a given load for a given period of time. The hardness is measured by the amount of penetration of the needle in the sample. Using this test, it has been found that an adequate range of hardness for the sealing compound is between 0.01 and 0.3 millimeters when using a 100 gram load on the inserted needle for 5 seconds in the sealing compound heated to 25 ° C (0.01-0.3 mm, per 100g / 5 seconds / 25 ° C). The sealing compound 14 is relatively inert so as not to react with the material stored in the container or with the heat generated during the manufacture or use of the product. The sealing compound 14_ also contains minimal volatile organic compounds and therefore does not present a threat to the environment. In addition, the sealing compound 14 diffuses relatively easily and equally on the inner surface of the container 10. According to the foregoing, the sealing compound preferably has a viscosity of between 1.0 to 200 centipoise (cp) and more preferably 150 cp, in a Brookfield Thermosel at 190 ° C, to ensure full coverage. In the preferred embodiment, the sealing compound 14 is specifically adapted for use with products that are heated during manufacture or generate heat during use. For example, candle wax is typically heated to about 70 ° C during its manufacture so that it can be easily poured into containers. When the candle subsequently burns, the wax melts at approximately 50-80 ° C. The melting point of the sealing compound 14 is therefore greater than at least 80 ° C and is preferably not less than about 102 ° C for applications including heat. It has been found that a mixture of synthetic wax and adhesive material creates a sealing compound having the above-mentioned characteristics. The sealing compound can be generally identified as a melted hydrocarbon spraying compound comprising a mixture of a polyethylene such as synthetic wax and an alkylated cycloaliphatic hydrocarbon as the adhesive. In the most preferred mode, the synthetic wax is a polyethylene such as that sold by Eastman Chemical Company of Kingsport, Tenesses under the trade name "EPOLENE N-14", however similar products (such as "EPOLENE N-10", "EPOLE? E N-21"and" EPOLE? E? -20") or other known substitutes. The adhesive is preferably an alkylated cycloaliphatic hydrocarbon such as that sold by Eastman under the tradename "EASTOTAC RESI? H-100R", although similar products (such as "EASTOTAC RESI? H-100E") or other known substitutes may also be used. The appropriate proportions of synthetic wax and adhesive are used, so that the sealing compound adheres to the container 10 and displays the desired characteristics noted above. It has been determined that a mixture, by weight, of about 10-90% polyethylene and a corresponding 90-10% alkylated cycloaliphatic hydrocarbon forms a melted hydrocarbon spray seal composition which is suitably bound to the inner surface and seals the seams of the container 10. In the most preferred embodiment, the sealing compound comprises 50% synthetic wax and 50% adhesive. Significantly, the wax and adhesive mixture contains minimal volatile organic compounds and therefore does not pose a threat to the environment. The present invention also provides an automatic method for sealing a three-piece container IQ with sealing compound. The method comprises heating and pressurizing the sealing compound such that it is sufficiently flowable for discharge through the nozzle 50. The preferred melted hydrocarbon compound described above is heated to a temperature of about 102-190 ° C to melt the sealing compound. The compound is then pressurized to about 1000 psi and pumped through a nozzle 50 to the interior surface of the container 10. As noted above, the compound preferably has a viscosity of about 1.0-200 cp in a 190 ° Thermosel Brookfield. C. The relatively low viscosity of the sealing compound 14 not only allows the compound 14 to be sprayed, but also ensures that the compound will be properly sprayed to cover the entire interior surface. To apply the sealing compound to an uncoated container, the nozzle 50 is inserted into the container near the base 16, as shown in Figure 4. The sealing compound 14 is pumped through the nozzle 50 and directed towards the inner surface of the container 10. The nozzle continues to spray the sealing compound as it is pushed towards the upper part 51 of the container 10, so that the entire inner surface is covered (Figure 5). The nozzle 50 has a round hole 52 dimensioned to coat the inner surface with a sufficient thickness of sealing material. For example, as shown in Figures 4 and 5, the side wall 18 of the container 10 has a generally square shape, and therefore the orifice of the nozzle 52 must be sized to reach the corners of the container 10. It has been found that A diameter of the nozzle orifice of approximately 0.03-0.07"is sufficient to cover distances up to 3 inches from the center of the nozzle.The sealing compound 14 should also be applied in the proper thickness. The melted hydrocarbon must be applied thick enough to completely cover the inner surface of the container, the sealing compound loses some of its flexibility and tends to crack and come out of the container 10 if it is applied too thick.According to the foregoing, it has been found that the Sealing compound should be applied in a thickness of between approximately 0.03-0.08"to prevent cracking. In the preferred embodiment, the sealing compound has a thickness of approximately 0.05. "During the sealing operation, the container 10 can be heated to ensure that the interior surface is fully covered with the sealing compound 14. For larger sized containers in particular, it has been found that the melted sealing compound cools as it passes from the nozzle towards the interior surface. The cooling increases the viscosity of the sealing compound, thereby reducing the amount of the indoor surface area covered. To help ensure maximum coverage, the container 10 is heated to maintain the temperature and therefore the viscosity of the sealing compound 14. In this embodiment, the container 10 is preferably heated to approximately 125 ° C. To further improve the coverage of the inner surface, the container 10 is rotated during the spraying. As noted above, the sealing compound has a preferred viscosity that allows the compound to be sprayed once it contacts the container 10. In a preferred embodiment, the container 10 is rotated during spraying to increase the amount of spray and therefore coating the surface more reliably - complete interior. Although any amount of rotation is beneficial, the container 10 is preferably rotated at speeds of at least 100 rpm to provide more consistent coverage. The rotation of the container 10 ensures that the sealing compound diffuses before it cools. From the foregoing, it will be appreciated that the present invention brings to the material a sealed metal container reliably retaining materials of relatively low viscosity. The inner surface of the container is coated with a sealing compound that retains materials of relatively lower viscosity. The sealing compound comprises a mixture of synthetic wax with sufficient adhesive so that the compound sticks to the surface of the container and seals the seams to prevent material from spilling out of the container. In addition, the sealing compound is not dangerous. The present invention also provides an automatic method for sealing a metal container sewn with the sealing compound. The method comprises heating and pressurizing the sealing compound so that it can be sprayed through a nozzle. The nozzle is placed inside the uncoated container and discharged as it passes the height of the container to cover the interior surface. The container can be preheated and turned during the spraying to cover with. more safety the entire interior surface.

Claims (19)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. A sealed metal container for holding a material of relatively low viscosity, the container comprising: a base having sides, upper and lower, a formed side wall member that engages the upper side of the base to form a lower seam, embedding the opposite ends of the side wall member with one another to form a side seam, the side wall member defining the top side an inner surface of the container, and a sealing compound including a mixture of synthetic wax and adhesive, having the compound a sufficient fraction of adhesive to allow the compound to be bonded to the inner surface of the container, the sealing compound having when bonded, a flexibility of approximately 10 to 20 pounds per inch, a hardness of approximately 0.01 to 0.3 mm for 100g / 5 seconds / 25 ° C and a melting point of at least 80 ° C.
2. 2. The sealed container according to claim 1, characterized in that the melting point of the sealing compound is at least 102 ° C.
3. 3. The sealed container according to claim 1, characterized in that the flexibility of the sealing compound is about 12 pounds per inch.
4. 4. The sealed container according to claim 1, characterized in that the sealing compound has a viscosity of about 1.0 to 200 cp in a Brookfield Thermosel at 190 ° C.
5. 5. The sealed container according to claim 1, characterized in that the sealing compound is applied to the container with a thickness between about 0.03 and 0.08 inches. The sealed container according to claim 1, characterized in that the sealing compound is applied to the container within a thickness of approximately 0.05 inches. 7. The sealed container according to claim 1, characterized in that the synthetic wax is a polyethylene. 8. The sealed container according to claim 7, characterized in that the adhesive is an alkylated cycloaliphatic hydrocarbon. The sealed container according to claim 1, characterized in that the sealing compound comprises between about 10-90% wax - - synthetic and between approximately 10-90% adhesive. The sealed container according to claim 1, characterized in that the sealing compound comprises about 50% synthetic wax and about 50% adhesive by weight. 11. A method for sealing a stitched metal container to hold a material of relatively low viscosity, the container including a base having an upper side, a formed side wall member, attached to the base to form a lower seal, opposite ends of the container. side wall member joined together, the side wall member defining and the top side an inner surface of the container, the method comprising the steps of: a. mixing a sufficient amount of adhesive with a synthetic wax to form a sealing compound adapted to be attached to the inner surface of the container, the sealing compound having a flexibility of about 10 to 20 pounds per inch, a hardness of about 0.01 to 0.3 mm for 100g / 5 seconds / 25 ° C and a melting point of at least 80 ° C; b. melting the compound at a temperature between about 80 to 190 ° C; c. pressurize the compound to approximately 1000 psi, and d. spraying the compound through a nozzle while directing the nozzle towards the interior surface of the container to coat the container with a thickness of approximately 0.03 to 0.08 inches. The method according to claim 11, characterized in that the melting point of the sealing compound is at least 102 ° C, and the melting step is carried out at a temperature between about 102 ° C to 190 ° C. 13. The method according to claim 11, characterized in that the nozzle has a hole with a diameter of approximately 0.03 to 0.07 inches. The method according to claim 11, characterized in that it further comprises the step of preheating the container to at least 125 ° C before step d. 15. The method according to claim 11, characterized in that the container is rotated between 1 and 100 rpm during stage d. The method according to claim 11, characterized in that the synthetic wax is a polyethylene 17. The method according to claim 11, characterized in that the adhesive is an alkylated cycloaliphatic hydrocarbon. The method according to claim 11, characterized in that the sealing compound has a viscosity between about 1-200 cp in a Thermosel - Brookfield at 190 ° C. The method according to claim 11, characterized in that the thickness of the sealing compound is about 0.05 inches.